Cell Structure and Function

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Cell Structure and Function

• Textbook Sections 7.1 and 7.3
• These cells are Neurons

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2 Ways to Make Mice

• In medieval Europe there were lots of mice around
  and farmers stored grain in thatched roofs barns.
  As a roof aged, it started leaking leading to
  spoiled or moldy grain.
• Conclusion Mice came from the moldy grain.

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How do you Make Frogs?

• Every spring, the Nile River flooded areas of
  Egypt, leaving behind nutrient-rich mud that
  enabled the people to grow that year's crop of
  food. However, large numbers of frogs also
  appeared.
• Conclusion Muddy soil gave rise to frogs

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Spontaneous Generation

• The idea that nonliving material can produce life
• The famous Greek philosopher Aristotle
  (384-322BC) believed insects are generated
  spontaneously from dew on leaves in spring, and
  mollusks formed by spontaneous generation in mud,
  sand, slime, or rock crevices

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Spontaneous Generation

• Was believed true until the mid 1600s when
  Francesco Redi showed that maggots came from
  flies not meat

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Before Microscopes

• People believed in spontaneous generation
• People believed that diseases were caused by
  spirits and curses
• Microorganisms, such as bacteria, were never
  thought of as a cause of diseases

Legionella
Anthrax
MRSA
Intestinal Bacteria
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Early Microscopes

• Anton van Leeuwenhoek invented a simple light
  microscope in the 1600s with one lens
• Using his microscope was the first person to
  discover microorganisms in water
• This was very important in the
  discovery of what caused diseases
  illnesses from drinking contaminated
  water

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Light Microscopes

• Microscopes were improved with higher quality
  lenses and multiple lenses and resulted in the
  compound light microscope similar to the ones we
  use
• Objects can be multiplied up to 1500 times
• Uses light to illuminate the object being viewed

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Discovery of Cells

• 1665 Robert Hooke examined cork with a compound
  microscope found it to perforated porous
  made of many little boxes
• He then looked at stems of trees, carrots ferns
  found similar little boxes that reminded him
  of the small rooms that monks lived in called
  cells.

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Other Scientists Added Their Discoveries

• 1830s Matthias Schleiden observed that plants
  are made of cells
• Theodor Schwann found animals are made of cells
• Rudolf Virchow reasoned that cells only come from
  other cells

Ameoba
Embryonic Stem Cells
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Cell Theory

• Putting the four scientists discoveries together
  gave us the Cell Theory
• All organisms (plants and animals) are composed
  of one or more cells (Schleiden and Schwann)
• The cell is the basic unit of structure and
  organization of organisms (Hooke)
• All cells come from preexisting
  cells (Virchow)

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Electron Microscopes

• Developed in the 1930s
• Uses a beam of electrons to magnify up to 500,000
  times
• 3 types
• SEM scanning electron microscope shows 3-D
  surfaces
• TEM transmission electron microscope allows
  the cells interior to be seen
• STM scanning tunneling microscope creates
  computer images of the surface atoms

Virus Dust mite
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What are these?

• Pollen Grains

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Sand magnified 250x
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Dust
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Butterfly Eggs
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Mosquito Head
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Eyelashes
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Frost
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Two Different Cell Types

• Prokaryotic cells do not contain membrane-bound
  organelles, are mostly unicellular small
• Eubacteria and Archaebacteria
• Eukaryotic cells have membrane-bound organelles
  and are mostly multicellular
• Plant
• Animal
• Fungus
• Protists

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Prokaryotic Cells

• No nucleus DNA floats free in the cytosol
• Flagella for movement
• Pili for reproduction and attachment

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Plant Animal Cell Organelles
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You are built out of cells!!!

• Atoms ? elements ? molecules ? organelles ? cells
  ? tissues ? organs ?organ system ? organism
• Your cells make new cells
• 200 million new cells per minute!
• 300 billion new cells EVERY DAY!!

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Some types of cells your body makes
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Nucleus

• Leader of the cell
• Contains directions to make proteins which all
  cell parts depend upon
• Contains chromatin strands of genetic material
• Largest membrane bound organelle
• Surrounded by Nuclear Membrane and perforated
  with nuclear pores

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Chromatin

• Master set of directions for making proteins
• During cell division, chromatin condenses to make
  chromosomes
• Strands of DNA
• - the genetic
• material

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Nucleolus

• Found inside the nucleus
• Produces ribosomes
• Is a combination of DNA and proteins
• Condenses into chromosomes for replication

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Ribosomes

• Ribosomes produce proteins following directions
  from the DNA
• Ribosomes do NOT have a membrane
• made of RNA and protein
• Ribosomes must leave the nucleus to make proteins
  in the cytoplasm

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Rough Endoplasmic Reticulum

• Site of all chemical reactions
• Series of folded membranes
• Folding allows a large amount to fit in a small
  space
• Ribosomes are attached to the surface
  of the Rough ER they synthesize
  protein
• Proteins are either exported from the
  cell or inserted into the cell membrane

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Transport Organelles
Nuclear Membrane
Smooth
Cell Membrane
Vesicle
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Golgi Apparatus

• Sorts, packages and secretes
• Proteins are transferred to the Golgi Apparatus
  after being made by the ribosomes on the Rough ER
• System of membranes that looks like a stack of
  pancakes
• Sorts proteins and packages them into membrane
  bound vesicles
• Like sorting mail at the post office

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Vesicles

• Pinch off from the Golgi Apparatus
• Transportation bubble for proteins and other
  large molecules

Golgi Apparatus
Vesicles
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Lysosomes

• Membranous sacs of digestive enzymes
• Lysosomes break down cellular materials and worn
  out cell parts
• Transport into and out of cell
• Common in animal cells, rare in plant
  cells
• Create fingers on human embryos by
  digesting the web between the fingers

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Cytoplasm

• Clear, gelatinous fluid inside cell that suspends
  all of the organelles (organelles float in
  cytoplasm)
• Ribosomes and RNA enter the cytoplasm through
  nuclear pores in the nuclear membrane

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Cell Membrane

• Allows selected materials to pass into and out of
  the cell
• Made of phospholipids
• All cells have cell membranes

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Nuclear Envelope

• Nuclear Envelope is a double membrane made of 2
  phospholipid bilayers
• Ribosomes and RNA pass through nuclear pores

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Smooth Endoplasmic Reticulum

• Smooth ER has no ribosomes attached and produces
  and stores lipids
• Involved in chemical regulation

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Reproduction Organelle
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Centrioles

• Used to move chromosomes during cell division
• Only found in animal cells

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Energy Organelles
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Chloroplasts

• Found in plants, algae, and some protists
• Capture sunlight and converts that energy to
  chemical energy
• Has a double membrane
• Stacks of individual thylakoids form grana and
  they trap the suns energy
• Contain chlorophyll light energy trapping
  pigment

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Mitochondria

• Membrane bound organelles in plant and animal
  cells
• Provides energy for cell usage
• Highly folded inner membrane
• Number of mitochondria in a cell depends on cells
  function
• Muscles have more than skin cells because they
  need more energy

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Structure and Movement Organelles
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Cell Wall

• An inflexible barrier that protects the cell and
  gives it support
• Found in plants, fungi, bacteria, and some
  protists
• Located OUTSIDE the plasma membrane
• Composed of cellulose (a carbohydrate)
• Porous allowing molecules to enter

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Vacuoles and Storage

• Membrane bound compartment
• Temporary storage for water and other materials
• Provides structural support for the cell
• Found mostly in plant cells (not in many animal
  cells)

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Cytoskeleton

• System of structure and support
• Skeleton of tiny rods and filaments
• Microtubules are thin, hollow cylinders made of
  protein
• Microfilaments are smaller, solid protein fibers

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Cilia

• Short, numerous, hairlike organelles made of
  microtubules
• Function in movement
• Extend from cells surface
• Found in eukaryotic and prokaryotic cells
• Present in the lining of human respiratory tracts

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Flagella

• Long, whip-like, less numerous extensions from
  the cells surface
• Function in movement

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Organelles unique to plants or animals
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Animal Cell
Vesicle
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